Field of the Invention
This invention relates to an automatic performance apparatus and method and, more particularly, to control of the fast forward and rewind of automatic performance.
Description of the Related Art
A conventional automatic performance apparatus is comprised basically as follows. A plurality of sets of musical information and time information are stored in a sequence memory and read out. A time counter is provided for counting elapsed time, and a clock signal at a predetermined frequency is supplied to the time counter. The count of the time counter and the read-out time information are compared. If the counted value becomes greater than the time information, a routine based on the music information for instance a sounding start or end routine, is executed. The above sequence of operations is repeatedly executed by reading out subsequent sets of music information and time information.
Of the conventional systems, there are two kinds of apparatuses which control the fast forward and rewind of automatic performance. FIG. 11 shows one kind of apparatus. The apparatus has a low frequency clock generator 91, which generates a clock signal at a usual low frequency, and a high frequency clock generator 92, which generates a clock signal at a high frequency. These clock signals at the low and high frequencies are supplied by a switching circuit 93 and a bus line to the time counter 94 noted above. The switching circuit 93 selects the high frequency clock signal when fast forward/rewind is designated, and it selects the low frequency clock signal in the absence of the fast forward/rewind designation. When there is a fast forward/rewind designation, the time counter 94 is incremented at a higher rate. Consequently, the automatic performance proceeds at a higher speed. In the rewind case, the music information and time information are read out reversely.
FIG. 12 shows the other kind of apparatus. The apparatus has a frequency divider 96, to which a clock signal generated from a clock generator 95 is input for conversion to a usual low frequency clock signal and a high frequency clock signal. These clock signals at the high and low frequencies are supplied through a switching circuit 97 and a bus line to the time counter 94. The switching circuit 97 selects the high frequency signal when fast forward/rewind is designated. Otherwise, it selects the low frequency clock signal in the absence of the fast forward/rewind designation. When fast forward/rewind is designated, the time counter 94 is incremented at a higher rate as in the above case, thus causing the automatic performance to proceed fast at an increased speed. In the rewind case, the music information and time information are read out in reverse.
In the above two kinds of apparatuses, however, it is necessary to provide the high frequency clock signal in addition to the usual low frequency clock signal. This means that either a plurality of clock generators 91 and 92 or a frequency divider 96 have to be provided, thus complicating the circuit construction and leading to cost increase.
An object of the invention is to dispense with a circuit for generating a high frequency clock signal, thus simplifying the circuit construction while readily permitting control of fast forward/rewind of automatic performance.